Windscreen wiper system

ABSTRACT

A windscreen wiper system, designed in particular for road vehicles, providing a non-circular path of any one of the points of at least one windscreen wiper blade and comprising a shaft having an alternating rotational movement which drives a main guide arm associated with the said shaft by a pivot joint, characterized in that it comprises, on one hand, a rocker (2) associated with the main guide arm (3) by a further pivot joint and, on the other hand, a secondary guide arm (4) articulated at two of its points, each articulation comprising at least two pivot joints, one of the above-mentioned articulations connecting it to the rocker (2), the blade (1) being articulated by a pivot joint on the rocker (2).

The present invention relates to a windscreen wiper system designed forvehicles, in particular for road vehicles. This system is characterisedby a non-circular path of any one of the points of the windscreenwiper(s) associated therewith. A path of this type is designed toimprove visibility and cleaning quality with respect to conventionalsystems having a circular path.

A number of systems having a non-circular path have been proposed. Theseinclude in particular the systems described in the French PatentSpecification Nos. 2 239 873, 2 194 173, 2 178 682 and 1 178 683. Thesesystems are characterised in particular by the presence of a singleblade articulated on a single blade-holder arm whose axis of rotation isdisplaced.

Other windscreen wiper systems designed to provide a wiping area ofrectangular shape have been proposed. These basically involve thesystems defined in the patent Nos. 2 131 446 and 2 144 269. Theorganisation of these systems is substantially different from thatdescribed in the patents mentioned in the preceding paragraph. Thesesystems basically contain a guide arm, in addition to a blade and ablade-holder arm. The mechanical arrangement of these elements is suchthat the articulation of the blade on the blade-holder arm describes arectilinear path and the guide arm maintains the axis of the blade infixed direction perpendicular to this path.

None of the systems mentioned above have as yet been put into practice,basically because their construction has proved to be uneconomical,their size prohibitive or their service life problematical.

The invention proposed uses a mechanical arrangement which associatestwo closed kinematic chains having certain elements in common whichconstitutes a mechanism having two input movements.

A first kinematic chain is constituted by a shaft rotating with respectto the bodywork, a main guide arm articulated on this shaft via a pivotjoint, a rocker articulated on one hand on the guide arm and, on theother hand, on the blade--possibly divided--by means of pivot joints.All the elements of this chain are contained in a plane containing theaxis of the shaft or parallel to this shaft. This plane is provided withan oscillating movement by means of the shaft which constitutes theinput element of this first kinematic chain.

The second kinematic chain comprises at least one element common to thefirst chain--the rocker--as well as its own elements--a secondary guidearm articulated at two points thereon, each articulation comprising atleast two pivot joints, one of the above-mentioned articulationsconnecting it to the rocker.

In a first variant, the articulation of the secondary guide arm whichdoes not provide the connection of the said arm with the rocker mayconnect the said arm to a crankshaft mounted pivotably with respect tothe bodywork. The crankshaft then constitutes the second input elementof the mechanism. The arrangement of the crankshaft is generally of anytype with respect to the axis of the input shaft of the first chain.Consequently, the movement of the secondary guide arm is spatial andtakes place outside of the oscillating plane containing the blade.

In the case referred to, in which the blade wipes a plane window screen,perpendicular to the input shaft and parallel to the main guide arm, thefunction of the first kinematic chain is to set at all times the angularposition of the blade, and the function of the second chain is to compela given point of the blade to describe a path which diverges from acircumference. This spacing is defined by the excentricity of thecrankshaft, by the arrangement of the articulations of the rocker and bythe articulation of the axes of the shafts of the two kinematic chains.

This provides a first advantage of the invention. As a result of asuitable arrangement of these articulations, an amplification of themovement of the crankshaft is produced which sets the spacing of thecircular path. A considerable spacing may be obtained by a low degree ofexcentricity and the mechanism may be readily embedded in the bodywork.

A second advantage of the invention is provided in that the blade isarticulated on a rocker which may be small in size and in that thisrocker is articulated on two arms, one of which is directly pivoted onthe bodywork. Satisfactory guiding of the blade which is favourable tothe quality of the wiping is therefore obtained. This wiping by two armsis obtained without the visibility of the driver being impaired withrespect to conventional guide systems. The instantaneous positions ofthe secondary guide arm in effect have a fairly slight deviation fromthe main guide arm.

A third advantage of the invention lies in the possibility which theproposed mechanical arrangement offers with respect to obtaining aconsiderable deviation from the circular path without causing pivotingof the blade about one of its actual points, which is not the case withthe majority of the mechanisms proposed up to now.

A fourth advantage of the invention lies in the low weight of theelements of the system which cause the deviations from the circularpath. These deviations are thus obtained without producing excessivemoments of inertia at high wiping speeds.

In one embodiment, the mechanism of the invention comprises a motorreduction gear and two transmissions associated, on one hand, with themotor reduction gear and, on the other hand, with the two input elementsof the mechanism. The transmission which adjusts the oscillation of themain guide arm and the blade, converts the continuous movement ofrotation of the motor into an alternating movement of rotation having anamplitude equal to that of the wiping action. The second transmissionmay be similar to the first. It may also supply a continuous movement ofrotation whose frequency is equal or proportional to that of themovement of oscillation of the blade.

In a further embodiment, it is also possible to add two transmissionsdisposed in series rather than in parallel to the motor reducer gear.One of the transmission then receives its input movement from the othertransmission rather than directly from the motor reducer gear.

In a second variant of the system of the invention, and for certainwindscreen sizes, the desired effects may be achieved by simplifying thesystem as follows: the eccentricity of the crankshaft of the secondkinematic chain is cancelled out, the movement of this chain and thetransmission causing it thus becoming superfluous. The actual elementsof the second kinematic chain are then combined in a single secondaryguide arm articulated, on one hand, about the rocker and, on the otherhand, about an element which is fixed with respect to the bodywork ofthe vehicle.

In more complex applications, the system of the invention may be used toprovide wiping actions with several blades. In these applications, useis made of as many systems as there are non-circular paths to beprovided independently.

The drawing shows, by way of example, a particular embodiment of theinvention, comprising a single blade and a single main guide arm.

In this drawing:

FIG. 1 shows the upper portion of the system in a plane which issubstantially perpendicular to the windscreen reference plane,

FIG. 1A shows a detail of the articulation of the secondary guide arm onthe rocker,

FIG. 2 shows, in part section, the lower portion of the system of FIG.1,

FIG. 3 shows a view of the system of FIGS. 1 and 2 in a plane parallelto the windscreen reference plane.

The blade 1 is mounted in a detachable manner on the rocker 2 by meansof a conventional articulation or pivot for pivotal movement about anaxis D. The rocker 2 is connected to the guide arms 3 and 4 by therespective articulations 5 and 6. The articulation 5 is a pivot jointhaving its axis perpendicular to the median plane of the rocker 2. Thearticulation 6 is a spherical connection. The rocker/blade androcker/main guide arm articulation or pivot axes are parallel. Thearticulation point 6 is disposed between the two axes mentioned above(axis D and the axis of pivot 5).

The main guide arm 3 is articulated on the shaft 7 by means of a pivotjoint 8 and an assembly 9 secures the arm 3 to shaft 7 as in the case ofconventional mechanisms.

The secondary guide arm 4 is articulated on the crankshaft 10 by meansof two pivot joints 11 and 12 having perpendicular axes connected by anintermediate lever portion 13.

The shaft 7 and the crankshaft 10 are guided in rotation with respect tothe bodywork by pivot guides or bearings 14 and 15. Their movements aresynchronised by a transmission 16.

In a variant, the articulation 6 is provided by two pivot joints, one ofwhich is parallel to the axis 5.

As is evident from the description above and the drawings, the outer endof main guide arm 3 is connected to rocker 2 at pivot 5 whichconstitutes a first pivot connection. Rocker 2 is pivoted to blade 1 atD, which forms a second pivot connection. The pivot 12 betweencrankshaft 10 and secondary guide arm 4 forms a third pivot connection.

The invention uses a mechanical arrangement which associates two closekinematic chains having certain elements in common which constitutes amechanism having two input movements.

A first kinematic chain is constituted by the shaft 7 rotating oroscillating which respect to the vehicle body. The main guide arm 3 isconnected to this shaft 7 via a pivot joint 8, which is a pivot of thearm 3. The rocker 2 is articulated, on one hand, to the guide arm 4 and,on the other hand, to the blade 1 at pivot D. All the elements of thischain are contained in a plane containing the axis of the shaft 7 or areparallel to this shaft. There is oscillating movement of this plane bymeans of the shaft 7 which constitutes the input drive of this firstkinematic chain.

The second kinematic chain comprises at least one element common to thefirst chain, namely, the rocker 2, as well as its own elements, whichare the secondary guide arm 4 articulated at two points thereon, eacharticulation comprising two pivot joints, the spherical pivot 6permitting movement about at least two axes, and the pivots 11 and 12permitting pivotal movement about two axes.

In a first variation, the articulation 12 of the secondary guide armconnects the arm to a stubshaft of the crankshaft 10 which is mounted torotate or pivot with respect to the vehicle body. The crankshaft 10 thusconstitutes the second input element of the mechanism. The arrangementof the crankshaft 10 is generally parallel with and spaced from the axisof the input shaft 7 of the first chain, as shown at FIGS. 2 and 3.Consequently, the movement of the secondary guide arm 4 is spatial andtakes place outside of the oscillating plane containing the blade 1.

Where the blade wipes a plane window screen, perpendicular to the inputshaft 7 and parallel to the main guide arm 3, the first kinematic chaindetermines the angular position of the blade, and the second chaincauses a given point of the blade to describe a path which deviates froma circumference or arc having the axis of shaft 8 as its center. Thisdeviation is defined by the eccentricity of the crankshaft 10, by therelative locations of the articulations 5, 6 and D of the rocker, and bythe relative locations of the axes of the shafts 7 and 10 of the twokinematic chains.

As a result of a suitable arrangement of these rocker articulations 5, 6and D, an amplification of the movement of the crankshaft 10 is producedwhich causes the deviation from the circular path. A considerabledeviation can be obtained by a low degree of eccentricity so themechanism can readily be mounted in the vehicle body.

It will be noted that the blade 1 is articulated on a rocker 2 which canbe small in size and that this rocker is articulated on the two arms 3,4 which are directly pivoted on the vehicle body. The guiding by the twoarms 3, 4 is obtained without the visibility of the driver beingimpaired, relative to conventional guide systems. The instantaneouspositions of the secondary guide arm 4 deviate only slightly from themain guide arm.

It is to be appreciated that a considerable deviation from the circularpath can be obtained without causing the blade to pivot about a contactpoint with the windshield, which is not the case with the majority ofprior mechanisms.

In one embodiment, the mechanism of the invention comprises a motorreduction gear and two transmissions associated, on one hand, with themotor reduction gear and, on the other hand, with the two shafts 7 and10 of the mechanism. The transmission which controls the oscillation ofshaft 7 and thus the main guide arm 3 and the blade 1, converts thecontinuous rotation of the motor into an alternating rotation having anamplitude equal to that of the wiping action. The second transmissioncan be similar to the first and can also provide continuous rotation ofcrankshaft 10 at a frequency equal to or proportional to the oscillationof shaft 7 and the blade 1.

In a second variation of the system of the invention, and for certainwindscreen sizes, the desired effects can be achieved by simplifying thesystem as follows: the eccentricity of the crankshaft 10 is eliminated,which eliminates the need for driving the crankshaft 10. The actualelements of the second kinematic chain are then combined in a singlesecondary guide arm 4 articulated at one end to the rocker 2 at pivot 6,and at the other end at pivot 12, to an element which is fixed withrespect to the bodywork of the vehicle. The same effect is obtained bylocking crankshaft 10 so it cannot rotate.

We claim:
 1. Windscreen wiper system for a vehicle, for providing anon-circular wiping path for at least one windscreen wiper blade,comprising a main guide arm, a rocker, means pivotally connecting saidrocker to the main guide arm at a first pivot connection for pivotalmovement about an axis generally parallel to the windscreen, meanspivotally connecting the rocker to a wiper blade at a second pivotconnection spaced from and parallel to the first pivot connection, meansfor connecting the main guide arm to a drive shaft remote from saidrocker for oscillating the arm about an oscillation axis to move thewiper blade back and forth across the windscreen, and means for pivotingsaid rocker about said first pivot connection on said main guide arm,during oscillation of said main guide arm, to displace said second pivotconnection and the wiper blade relative to said oscillation axis, saidmeans comprising, a secondary guide arm pivotally connected to saidrocker at a location spaced from said first pivot connection, and pivotmeans for pivotally connecting an end of the secondary guide arm remotefrom the rocker for pivotal movement about a third pivot connectionspaced from said oscillation axis of the main guide arm.
 2. A systemaccording to claim 1 wherein said third pivot connection comprises apivot connection to a rotatable crankshaft on the vehicle.
 3. A systemaccording to claim 2, further comprising means for driving saidcrankshaft.
 4. A system as claimed in claim 1 wherein said third pivotconnection comprises a pivot fixed with respect to the vehicle.
 5. Asystem as claimed in claim 1 wherein the secondary guide arm ispivotally connected to the rocker at a location between said first andsecond pivot connections.
 6. A system according to claim 1 wherein saidthird pivot connection comprises an axis parallel to said oscillationaxis.
 7. A system as claimed in claim 1 wherein the secondary guide armis pivotally connected to said rocker for pivotal movement about axeswhich are perpendicular to each other.
 8. A system as claimed in claim 7wherein said second pivot connection comprises an axis in a planeperpendicular to said oscillation axis, and one of the pivot joints ofthe secondary guide arm on the rocker comprises an axis parallel to theaxis of the second pivot connection.
 9. A system as claimed in claim 7wherein the secondary guide arm is pivotally connected to said rocker bya spherical pivot.